Did some detective work to figure out why I had a flat issues at my last race. I checked the two tubes that went flat and discovered that one of them was from a puncture on the outside (thorn glass or sharp rock) and the other from the inside (a problem with my rim or rim strip). I thought I was dealing with one serial puncturer but I was wrong two puncturers had been responsible for foiling my last race. I did some more sleuthing to find a sharp area where the loop of the wheel came together. I sanded down the sharp spot, put a new rim strip on and checked for sharp objects in my tire. Hopefully this mystery is solved.